1998年秋季渤海中部及其邻近海域的网采浮游植物群落

The netz-phytoplankton community of the central Bohai Sea and its adjacent waters in autumn, 1998

研究了 1998年秋季覆盖渤海中部和渤海海峡及其邻近海域 30个测站两遍大面调查的网采浮游植物物种及其群落特征。经初步分析 ,共发现浮游植物 3门类 38属 84种 (不包括未定名物种 ) ,物种主要以硅藻为主 ,但甲藻在群落中的比重也很明显 ,在个别站位上会成为优势类群。优势物种主要为偏心圆筛藻 (Coscinodiscus excentricus)、梭状角藻 (Ceratium fusus)、洛氏角毛藻 (Chaetoceros lorenzianus)、浮动弯角藻 (Eucampia zodiacus)、叉状角藻 (Ceratium furca)、佛氏海线藻 (Thalassionemafrauenfeldii)、中华半管藻 (H emiaulus sinensis)、尖刺伪菱形藻 (Pseudo- nitzschia pungens)、布氏双尾藻 (Ditylum brightwellii)、粗刺角藻 (Ceratium horridum)、掌状冠盖藻 (Stephanopyxispalmeriana)和萎软几内亚藻 (Guinardia flaccida)。细胞丰度的平面分布由主要浮游硅藻的分布所决定 ,其高值区分布在渤海湾、渤海中部、莱州湾北部和渤海海峡南部。浮游甲藻在渤海湾北部和莱州湾北部等局部区域形成高值区 ,并影响浮游植物的平面分布。两遍大面站调查期间渤海浮游植物群落的结构是相对保守的 ,渤海浮游植物群落季节和周年的变化主要是物种演替过程。调查期处于浮游植物群落的负增长时期 ,其主要原因是物理水?

Features of phytoplankton community were studied based on the netz-phytoplankton data from the Sino-Germany Cooperative Project “Analysis and Modelling of the Bohai Sea Ecosystem”. Station-grid-surveys were carried out twice between 24^(th) September and 6^(th) October 1998, at 30 grid stations in the Bohai Sea, to understand the ecosystem structure and functions. Phytoplankton was sampled by the standing net type III (mesh size 76μm, the standard sampling tool in Chinese marine phytoplankton studies) with a vertical haul at each grid station. The phytoplankton samples were preserved in neutral formalin (2% final concentration of formaldehyde) and analysed in the laboratory using a microscope. Three classes, including 38 genera and 84 species (not including unidentified taxa) were commonly found in the survey area. The main phytoplankton group was diatoms, but the dinoflagellates were also important in the phytoplankton community, becoming the dominant group at some study stations. The dominant species were Coscinodiscus excentricus, Ceratium fusus, Chaetoceros lorenzianus, Eucampia zodiacus, Ceratium furca, Thalassionema frauenfeldii, Hemiaulus sinensis, Pseudo-nitzschia pungens, Ditylum brightwellii, Ceratium horridum, Stephaopyxis palmeriana and Guinardia flaccida, etc. Most are neritic species of temperate coastal seas, along with a few oceanic warm water species. The dominant species in the two station-grid-surveys were similar, so it can be deduced that phytoplankton community in the Bohai Sea in autumn was relatively uniform. Most of dominant phytoplankton species mentioned above are autochthonous species, which occur mainly locally. Hemiaulus sinensis, Stephaopyxis palmeriana and Guinardia flaccida are allochthonous species, imported via the Huanghai Sea Warm Current through the North Bohai Strait. These dominant species mentioned above are big-celled with high-carbon-content, most of them are key stone species in autumn in the Bohai Sea. A study of species population dynamics was necessary to understand the processes in the Bohai Sea ecosystem. Except for Coscinodiscus excentricus and Ceratium horridum, the species mentioned above are red tide organisms, with Ceratium fusus and Ceratium furca forming red tides in the Bohai Bay during the cruise. Phytoplankton cell abundance in the first station-grid-surve ranged from 4.14×10~4 ind./m^3 to 535.45×10~4 ind./m^3, the average value was 160.86×10~4 ind./m^3; it was high in the North Bohai Bay, the Central Bohai Sea, the North Laizhou Bay and the South Bohai Strait. Phytoplankton cell abundance in the second station-grid-survey ranged from 1.75×10~4 ind./m^3 to 226.10×10~4 ind./m^3, the average value was 77.84×10~4 ind./m^3; it was high in the Bohai Bay, the Central Bohai Sea, the North Laizhou Bay and the South Bohai Strait. Diatom cell abundance in the first station-grid-survey ranged from 3.30×10~4 ind./m^3 to 393.28×10~4 ind./m^3, the average value was 124.16×10~4 ind./m^3; it was high in the North Bohai Bay, the Central Bohai Sea, the North Laizhou Bay and the South Bohai Strait. Diatom cell abundance in the second station-grid-survey ranged from 1.63×10~4 ind./m^3 to 215.96×10~4 ind./m^3, the average value was 60.39×10~4 ind./m^3; it was high in the North Bohai Bay, the Central Bohai Sea and the South Bohai Strait. Dinoflagellate cell abundance in the first station-grid-survey ranged from 0.34×10~4 ind./m^3 to 234.23×10~4 ind./m^3, the average value was 36.69×10~4 ind./m^3; it was high in the North Bohai Bay. Dinoflagellate cell abundance in the second station-grid-survey ranged from 0.12×10~4 ind./m^3 to 144.20×10~4 ind./m^3, the average value was 17.45×10~4 ind./m^3; it was high in the Bohai Bay and the North Laizhou Bay. The horizontal distribution was quite similar between the two station-grid-surveys. The horizontal distribution of phytoplankton was determined by the diatom distribution pattern, dinoflagellates formed high abundance areas in the North Bohai Bay and the North Laizhou Bay and affected the phytoplankton distribution patt